/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.dubbo.metadata;

public interface MetadataChangeListener {
    /**
     * Call when metadata in provider side update <p/>
     * Used to notify consumer to update metadata of ServiceInstance
     *
     * @param metadata latest metadata
     */
    void onEvent(String metadata);

    /**
     * Echo test
     * Used to check consumer still online
     */
    default String echo(String msg) {
        return msg;
    }
}
